Clinical Review Lesson of the week

Bradycardia in acute haemorrhage

BMJ 2004; 328 doi: https://doi.org/10.1136/bmj.328.7437.451 (Published 19 February 2004) Cite this as: BMJ 2004;328:451
  1. Ian Thomas, specialist registrar (ThmsIa@aol.com)1,
  2. John Dixon, consultant2
  1. 1Department of Anaesthetics, Royal United Hospital, Bath BA1 3NG
  2. 2Department of Anaesthetics, Weston General Hospital, Weston-Super-Mare BS23 4TQ
  1. Correspondence to: I Thomas
  • Accepted 23 July 2003

Introduction

We describe three patients who all underwent elective surgery and had acute haemorrhage after the operation. All three patients had hypotension but did not develop the typically associated sign of tachycardia. The assumption that occult bleeding is always associated with tachycardia is incorrect and may lead to a delay in diagnosis.

The accepted and traditional cardiovascular signs of acute blood loss are tachycardia, hypotension, and poor peripheral perfusion. In a healthy adult, tachycardia is a heart rate of more than 100 beats/min. The maximum heart rate a person can sustain is generally accepted to be 220 minus the patient's age. Tachycardia occurs in the initial stage of a biphasic cardiovascular response, which attempts to maintain cardiac output in the face of hypovolaemia and a decreased stroke volume. Neural and hormonal mechanisms mediate this tachycardia after arterial baroreceptors are stimulated. In some patients with acute haemorrhage, however, this initial tachycardic response is absent; this may lead to confusion or a delay in diagnosis. The phenomenon has been called relative bradycardia,14 absence of tachycardic response,15 or paradoxical bradycardia.6 We describe three patients for whom doctors did not see initial tachycardia during acute haemorrhage.

Case reports

Case 1

A 59 year old woman had an elective total abdominal hysterectomy and bilateral salpingo-oophorectomy. Apart from mild asthma, for which she took a ventolin inhaler, she was otherwise fit and well. She was taking no regular drugs. Her preoperative blood pressure was 145/75 mm Hg, pulse rate was 76 beats/min, and haemoglobin concentration was 147 g/l. …

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